Term
| Which part of the orbit was first developed embryologically? |
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Definition
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Term
| Sphenoid bone was formed by which type of ossification? |
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Definition
| endochondral (preformed in cartilage and then ossified) and membranous (ossified from CT) |
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Term
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Definition
| support and provide protection to the orbit and soft tissue |
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Term
| The 7 bones that make up the orbit |
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Definition
Sphenoid
Frontal
Ethmoid
Maxillary
Zygomatic
Palatine
Lacrimal bones |
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Term
| Which orbital wall is the thickest? |
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Definition
| Lateral wall (zygomatic bone with tubercle where lateral canthal ligament, LR, LR muscle check ligament, and aponeurosis of levator palpebrae superioris muscle attach) |
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Term
| Which area of the orbit is the most susceptible to blunt force trauma? |
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Definition
| orbital floor (supported by the maxillary-ethmoid buttress and the infraorbital sulcus/canal) |
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Term
| What are the symptoms from a blow out fracture? |
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Definition
loss of vision
diplopia
enophthalmos (change in the position of the eye in the globe)
numbness of the cheeck |
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Term
| Which orbital wall is less susceptible to fracture eventho it's extremely thin, and why? |
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Definition
| Medial/Nasal floor; because of it's honeycombed structure |
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Term
| What is a tripod fracture? What are the symptoms seen? |
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Definition
A fracture along the suture line of the orbit due to blunt trauma to the cheek.
depressed cheek, muscle spasm, difficulty opening mouth |
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Term
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Definition
forward displacement of the globe
Most common cause is Grave's Diz where muscle and CT increase in size and fat content which eventually replaced by scar tissue-->pushing eye forward
Possible causes:
-severe myopia
-buphthalmos (infantile glaucoma) |
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Term
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Definition
Retro-displacement of the globe posterior into the orbit
Possible causes:
-Trauma
-Surgery
-previous irradiation
-metastatic lesion may lead to pseudoexophthalmos in the contralateral eye |
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Term
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Definition
| forward displacement of any object |
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Term
| Normal measurement of exothalmos |
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Definition
Normal: 15-17mm
Caucasians: 11-21
African-Americans: 12-24
Difference of >2mm bt 2 eyes is significant |
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